1. Field of the Invention
The present invention relates to a scroll type compressor for performing compression through the engagement between a fixed scroll and a movable scroll.
2. Description of the Related Art
In general, there is known a scroll type compressor that includes a fixed scroll and a movable scroll engaged with the fixed scroll, the fixed scroll and the movable scroll being accommodated in a hermetically sealed container, and compresses gas by rotating the movable scroll. The movable scroll is supported through an Oldham's ring by a housing (which is also called as a compliant frame. The Oldham's ring is a member for constraining the movable scroll so that the movable scroll makes a whirling motion, and a fitting pawl for fixing (fixing key) is fitted in a groove provided in the housing, whereby the Oldham's ring is fixed to the housing.
A recently known scroll type compressor is configured so that the Oldham's ring is not fixed to the housing, but fixed to the fixed scroll in order to enhance the assembling precision concerning the positioning (phase) of the fixed scroll and the movable scroll. In this structure, the fixing locking pawl extending from the Oldham's ring extends beyond the movable scroll and is fitted to the fixed scroll (see JP-A-2006-161818 and JP-A-2000-283067, for example).
However, in the above structure, the fixing locking pawl of the Oldham's ring is longer, and thus the fixing locking pawl is easily broken.
Furthermore, the movable scroll is located between the Oldham's ring and the fixed scroll, and thus the movable scroll is provided with an escape portion which avoids the fixing locking pawl extending from the Oldham's ring. However, when a chuck is fixed to the movable scroll to perform working, this escape portion obstructs this chuck fixing work.
Specifically, as show in FIG. 6, the movable scroll 125 is constructed by providing a lap 125B is provided to a circular mirror plate 125A. A pair of guide grooves for receiving and guiding a projecting portion provided to the Oldham's ring are formed in the mirror plate 125A so as to be displaced in phase by 180°, and right and left circumferential portions of the mirror plate 125A are cut out in parallel to the guide direction of the guide grooves 190, thereby forming escape portions 191. The processing of the lap, etc. of the movable scroll 125 is performed while three points Q1 to Q3 of the outer periphery of the mirror plate 125A which are respectively displaced in phase by 120° are gripped by a three-point chuck which is normally used in a machine work. However, when the three-chuck is secured to the outer periphery of the mirror plate 125A while avoiding the guide grooves 190 under the state of FIG. 6, any one of the points Q1 and Q3 invades into the escape portion 191, and thus the chuck can not be secured to the mirror plate 125A with avoiding the guide groove 190, which causes reduction in processing accuracy and processing efficiency.